Contents
Accessing variables programatically
The Ansible FAQ details how to build up varibles programatically.
{{ hostvars[inventory_hostname]['ansible_' + which_interface]['ipv4']['address'] }}In order to access concatenated variables they need to be in the inventory. This doesn’t happen with vars inline in the playbook but does work if you use include_vars
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- hosts: localhost
connection: local
vars:
test_app: admin
tasks:
- include_vars: concat_vars.yml
- debug:
msg: "admin port from inventory = {{ hostvars[inventory_hostname][test_app+'_port'] }}
admin_port: 1000TASK: [debug ] ****************************************************************
ok: [localhost] => {
"msg": "admin port from inventory = 1000"
}Dictionaries
The following example shows how you can iterate over a dict and access directly
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- hosts: localhost
connection: local
vars:
apps:
admin:
service: admin
handler: /admin
port: 1200
rpt:
service: rpt
handler: /rpt
port: 1234
tasks:
- debug:
msg: "{{ item.key }} -- {{ item.value.service }} {{ item.value.port }}"
with_dict: apps
- debug:
msg: "{{ apps.admin.service }}"
TASK: [debug ] ****************************************************************
ok: [localhost] => (item={'key': 'admin', 'value': {'handler': '/admin', 'port': 1200, 'service': 'admin'}}) => {
"item": {
"key": "admin",
"value": {
"handler": "/admin",
"port": 1200,
"service": "admin"
}
},
"msg": "admin -- admin 1200"
}
ok: [localhost] => (item={'key': 'rpt', 'value': {'handler': '/rpt', 'port': 1234, 'service': 'rpt'}}) => {
"item": {
"key": "rpt",
"value": {
"handler": "/rpt",
"port": 1234,
"service": "rpt"
}
},
"msg": "rpt -- rpt 1234"
}Looping over dictionaries
Sometimes its necessary to loop over a list of dictionaries. The following example has a dictionary with 3 keys
- name: Configure environment
template: src={{ item.src }} dest={{ item.dest }} mode={{ item.mode }} owner=root group=root
with_items:
- { src: 'hosts.equiv.j2', dest: '/etc/hosts.equiv', mode: '0644' }
- { src: 'informix.conf.j2', dest: '/etc/ld.so.conf.d/informix.conf', mode: '0444' }
- { src: 'informix.csh.j2', dest: '/etc/profile.d/informix.csh', mode: '0644' }
- { src: 'informix.init.j2', dest: '/etc/init.d/informix', mode: '0755' }
- { src: 'informix.sh.j2', dest: '/etc/profile.d/informix.sh', mode: '0644' }
notify:
- Reload ldconfigChecking if a value is in a multiple lists
We have a situation where we want to install applications on a number of hosts. This information needs to be available to all hosts as its used by Apache in the web tier and on the db tier. The information is stored in group_vars/all to allow global access.
app_layout:
admin:
groups: ['group-boapp-layout-A', 'group-boapp-layout-B']
rpt:
groups: ['group-boapp-layout-A']- name: Establish if application can be installed on host
set_fact:
install_app: true
when: inventory_hostname in groups[item]
with_flattened: app_layout.groups
- include: app.yml
when: install_app == trueThe fact install_app will only be set if the current inventory_hostname is in each of the lists. group-boapp-layout-A and group-boapp-layout-B expand to
"all": [
"ec2-test-boapp03",
"ec2-test-boapp04",
"ec2-test-boapp01",
"ec2-test-boapp02"
],
"group-boapp-layout-A": [
"ec2-test-boapp01",
"ec2-test-boapp02"
],
"group-boapp-layout-B": [
"ec2-test-boapp03",
"ec2-test-boapp04"
],TASK: [app-appserv | Establish if application can be installed on host] ***
skipping: [ec2-test-boapp03] => (item=group-boapp-layout-A)
skipping: [ec2-test-boapp04] => (item=group-boapp-layout-A)
ok: [ec2-test-boapp02] => (item=group-boapp-layout-A)
ok: [ec2-test-boapp03] => (item=group-boapp-layout-B)
skipping: [ec2-test-boapp02] => (item=group-boapp-layout-B)
ok: [ec2-test-boapp01] => (item=group-boapp-layout-A)
ok: [ec2-test-boapp04] => (item=group-boapp-layout-B)
skipping: [ec2-test-boapp01] => (item=group-boapp-layout-B)